The Collaborative International Dictionary of English v.0.48:

Expound \Ex*pound"\ ([e^]ks*pound"), v. t. [imp. & p. p.
   Expounded; p. pr. & vb. n. Expounding.] [OE. exponen,
   expounen, expounden, fr. L. exponere to set out, expose,
   expound; ex out + ponere to put: cf. OE. expondre, expondre.
   See Position.]
   1. To lay open; to expose to view; to examine. [Obs.]
      [1913 Webster]

            He expounded both his pockets.        --Hudibras.
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   2. To lay open the meaning of; to explain; to clear of
      obscurity; to interpret; as, to expound a text of
      Scripture, a law, a word, a meaning, or a riddle.
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            Expound this matter more fully to me. --Bunyan.
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WordNet (r) 3.0 (2006):

expound
    v 1: add details, as to an account or idea; clarify the meaning
         of and discourse in a learned way, usually in writing; "She
         elaborated on the main ideas in her dissertation" [syn:
         elaborate, lucubrate, expatiate, exposit,
         enlarge, flesh out, expand, expound, dilate]
         [ant: abbreviate, abridge, contract, cut,
         foreshorten, reduce, shorten]
    2: state; "set forth one's reasons" [syn: set forth,
       expound, exposit]